C-Jun N-terminal kinases
c-Jun N-terminal kinases (JNK) , also stress-activated phospho-kinases (SAPK), are important enzymes for the cellular transmission of stimuli ( signal transduction ), especially stress signals . Their name is derived from the ability to phosphorylate N-terminal amino acid residues of c-Jun . Biochemically, JNKs belong to the protein kinases of the MAP kinase family.
JNKs are integrated into a signal cascade. At the beginning of this signal cascade are u. a. Stress factors such as UV radiation, interleukins or chemokines and numerous others. This also explains the term "stress kinases". However, research has now shown that JNKs also play an important role in a variety of physiological processes.
There are three types of JNKs, with JNK1 and JNK2 being further subdivided into a 46 kDa variant and a 54 kDa variant by alternative splicing . A total of ten isoforms are known. The individual isoforms phosphorylate other proteins. A scaffold protein such as JIP (JNK-interacting protein) is often required to perform this function.
Cellular targets for JNKs are probably proteins in the cell nucleus (in particular the phosphorylation of c-Jun, which as AP-1 regulates gene expression), proteins of the cytoskeleton of the cell, and proteins with the BH3 motif . Of the latter, the anti-apoptotic Bcl-2 is inactivated by phosphorylation, and pro-apoptotic factors such as Bax are activated.
Individual evidence
- ↑ Waetzig V, Herdegen T: Context-specific inhibition of JNKs: overcoming the dilemma of protection and damage . In: Trends Pharmacol. Sci. . 26, No. 9, September 2005, pp. 455-61. doi : 10.1016 / j.tips.2005.07.006 . PMID 16054242 .
- ↑ Swiss Institute of Bioinformatics (SIB): PROSITE documentation PDOC01049. Retrieved September 26, 2011 .